This invention relates to medical devices and, in particular, to devices, systems, and methods for delivery of a medical device into the human or animal vasculature by endovascular technique, and is particularly suited to deploying a stent graft where it may be necessary to catheterize a side branch vessel from a main vessel, for example, catheterizing the iliac artery from a contralateral iliac artery in order to deploy a stent graft. However, the invention is not limited to this example and may be utilized in any lumen where such catheterization is required.
Stent grafts are used to treat the vasculature in a human body or an animal body to repair or bypass a defect in the vasculature. For instance, a stent graft may be used to span an aneurism in an artery. In some instances, however, such a damaged or defective portion of the artery may include a branch vessel such as an internal iliac artery. A stent graft spanning the length of the aneurism may cause further complications if the stent graft does not provide blood flow into the branch vessel. To provide blood flow into the branch vessel, a side branch on a branched stent graft or fenestrated stent graft can be positioned over the opening to the side vessel and then another stent graft can be deployed through the side branch or the fenestration into the side vessel. Blood can then flow through the branched stent graft into the branch vessel through the side branch. Exemplary branched and fenestrated stent grafts, and their delivery systems are disclosed in U.S. Publication No. 2013-0131777, which is incorporated by reference herein in its entirety, and in particular FIGS. 1-23 and newly added FIG. 24 and the accompanying text. Further exemplary fenestrated stent grafts and their delivery system are disclosed in co-pending application Ser. No. 11/600,655, and in particular new FIGS. 9-12, which application is incorporated by reference herein in its entirety.
Using the Seldinger technique, a branched stent graft can be deployed into the common iliac artery by way of the femoral artery. During the positioning of the branched stent graft, it is necessary to align the side branch with the side vessel. A leg extension is then placed in the side vessel through the side branch. To align the branched stent graft and place the leg extension, it is beneficial to use a guidewire extending through the side branch and laterally into the side vessel.
Some systems and techniques to extend a guidewire laterally into the side vessel include a delivery system having the nose cone dilator shown in FIGS. 1 through 3. One example of such a system is shown in U.S. Publication No. 2009-0105801 A1, incorporated herein by reference in its entirety. In FIG. 1, the proximal end 100 of the delivery device is shown. The device includes a nose cone dilator 102 having a groove formed into the nose cone dilator 102. A curved pre-loading guiding catheter 106 and a guide-wire 108 (shown in FIG. 3). The curved guiding catheter 106 is disposed in a groove 104 formed into the nose cone dilator 102 and is biased to extend laterally such that its natural position directs the guidewire 108 in a specific direction (e.g., toward the contralateral iliac for an iliac branch device). The guide-wire 108 can then be extended laterally through the curved guiding catheter 102 when the nose cone dilator 102 is in place, thereby facilitating snaring the guidewire and a creating a through-wire for device alignment and/or facilitating the delivery of a bridging stent. As shown, a retractable sheath 110 is disposed over a portion of the dilator tip.
In FIG. 1, the curved guiding catheter 106 is not constrained and extends from the nose cone dilator 102 during sterilization and shipping. This allows the curved guiding catheter 106 to retain its curved shaped following sterilization and storage. If the curved guiding catheter 106 were to be constrained to a straight shape during sterilization and shipping, there is a potential that the curved guiding catheter 106 could lose its curved shape.
As shown in FIG. 2, when the delivery system is ready for use, the sheath 110 is advanced over the curved guiding catheter 106 to constrain the curved guiding catheter 106 such that it no longer extends outside of the sheath 110. If the curved guiding catheter 106 were to remain extended from the nose cone dilator 102 during delivery, it is possible that the curved guiding catheter 106 could be damaged or interfere with the guidance of the delivery system.
Once the device is delivered to the desired treatment site as shown in FIG. 3, the sheath 110 is retracted distally and the curved guiding catheter 106 returns to its natural shape extending laterally from the nose cone dilator 102. The guidewire 108 can then be extended laterally.
Preparing such a delivery system requires at least one additional step. Because the proximal most part of the guiding catheter must retain its curved shape, at least part of it must protrude from the main body tip outside of the sheath for shipping and storage. This ensures that the pre-formed curve will be maintained. Hence prior to inserting the delivery system, the sheath 110 must be advanced over the curved guiding catheter 106 tip to completely sheath it. As described above, the delivery system cannot be packaged with the sheath 110 restraining the curved guiding catheter 106, as the curved guiding catheter 106 may lose its shape over time. Furthermore, the curved tip must be re-sheathed so that it is protected as it advances through the body vessel.